JPS5879947A - Manufacture of acetic acid anhydride - Google Patents

Abstract

Methyl acetate is carbonylated to acetic anhydride with carbon monoxide, in liquid phase, in an anhydrous reaction medium, in the presence of a catalytically effective amount of (i) nickel, (ii) methyl iodide, (iii) an alkali metal iodide, and (iv) a crown ether.

Description

[Detailed description of the invention] The present invention relates to a method for producing acetic anhydride.

More particularly, the invention relates to a process for producing acetic anhydride by carbonylating liquid phase methyl acetate in an anhydrous medium in the presence of effective nickel, methyl iodide, alkali metal iodide and crown ether.

The method of the invention requires the presence of an effective amount of nickel. Any nickel source can be used within the scope of the invention. Nickel may be introduced in metallic form (eg Raney nickel) or in any other convenient form. Examples of nickel compounds which may be useful in the practice of this invention are carbonates, oxides, hydroxides, halides, especially iodides, and carbzanates, especially acetates of nickel.

However, when a nickel salt is introduced, a long or short-term reaction period is observed, so it is preferable to use nickel-free compounds such as nickel tetracarbonyl and bis(trinoenylphosphine)nickel dicarbonyl.

Of course, one skilled in the art would find it easy to select a suitable form of nickel compound, and the exact form of nickel to be introduced into the reaction medium is a less important factor, especially when produced in a continuous process. You will also notice that it does not work.

The amount of nickel is not a critical factor. The proportion of nickel that influences the reaction rate is determined according to the reaction rate deemed appropriate, taking into account other reaction parameters. Generally, good results are obtained using 5 to 2.000 milligram atoms of nickel per solution 11. It is desirable to carry out the reaction at a ratio of 20 to 1.000 milligram atoms of nickel per 11 parts.

In practicing this invention, methyl iodide must also be present in the reaction medium. It is not necessary to introduce this component of the catalyst system at the start of the reaction; it is also possible, for example, to use free iodine, hydriodic acid, alkyl iodides other than methyl iodide, or acyl iodides. As those skilled in the art will be aware, iodine and these types of iodine compounds can be considered precursors to methyl iodide in the reactions of the present invention; generally, each gram atom of nickel contained in the reaction medium methyl iodide is present in the medium in an amount of 1 to 100 mol, preferably 5 to 50 mol.

The catalyst systems used in the present invention also include alkali metal iodides. Preferred alkali metal iodides are sodium iodide or potassium iodide.

Generally, the alkali metal iodide is used in an amount of 0.2 to 50 moles per gram atom of nickel contained in the reaction medium; It is preferred to use and advantageously amounts from 1 to 10 moles per gram atom of nickel.

Catalyst systems used within the scope of the present invention also include crown ethers. These compounds are macrocyclic polyethers that are known per se, and are represented by the following formulas (1) to (
III) in the above formula, m and n
is an integer such that the macrocyclic ring contains 3 to 20 oxygen atoms, a represents a phenylene, cyclohexylene, or 2,3-naphthylene group, and R is an alkyl group having 4 or less carbon atoms or hydrogen , and U and V, which may be the same or different groups, have the formula: %formula%() (where p is an integer that may be 0 such that the number of oxygen atoms contained in the ring is 20 or less) and q is 1 to 1
represents a group having an integer of 0 (preferably q equal to 2 when p is not 0).

In particular, for details regarding the manufacturing method of crown ethers, etc., please refer to the following literature.
the chemical 5ociety) 8
Volume 9, pages 7017 onwards (1967) -Chemical Reviews
ews) Vol. 74, No. 6, p. 351 et seq. (1974).

Examples of suitable crown ethers for carrying out the invention include 12-crown-4,15-crown-5,18-
Crown-6,21-Crown-7,24-Crown-
8, benzo-9-crown-6, benzo-12-crown-4, benzo-15-crown-5, benzo-18-
Crown-6, (t-butylbenzo)-15-crown-5, (t-butylbenzo)-18-crown-6, cyclohexyl-12-crown-4, cyclohexyl-
15-crown-5, cyclohexyl-18-crown-6, (t-butylcyclohexyl)-15-crown-5, (t-butylcyclohexyl)-18-crown-6, (2,6-naphtho)-15- Crown-5, (2
, 6-naphtho)-18-crown-6, dibenzo-14
-crown-4, dibenzo-15-crown-5, dibenzo-16-crown-5, dipenzo-18-crown-6, dibenzo-21-crown-7, dipenzo-24
-crown-8, dipenzo-60-crown-10, dipenzo-60-crown-20, di(t-butylbenzo)-18-crown-6, di(2,3-nando)-18
-crown-6, dicyclohexyl-18-crown-
6, di(1-butylcyclohexyl)-18-crown-6, dicyclohexyl-24-crown-8, dicyclohexyl-60-crown-10 and dicyclohexyl-60-crown-20. .
- The above formula (1) containing 5 to 10 oxygen atoms in the ring
It is preferable to use macrocyclic polyethers of ) to (It). Among the polyethers of formula (III), those in which U and V are the same group, q is equal to 2, p is 1.2 or an integer of O, and R is hydrogen are selected. desirable.

More particularly 15-crown-5 and 18-crown-6 are particularly suitable for practicing the invention.

The usage range of crown ether is wide. It has been found that there is no advantage to using more than one mole of crown ether per mole of alkali metal iodide. Generally, the amount of crown ether is from 1 molar part or more to 5 molar parts relative to the alkali metal iodide. The optimum amount of crown ether to be used largely depends on the type and amount of the alkali metal iodide used, and also varies depending on the properties of the crown ether itself, but it is approximately 10 to 75 mol based on the alkali metal iodide. This is the level of responsibility.

According to a particularly advantageous variant of the invention, an alkaline earth metal salt, preferably a lithium salt, is also included in the catalyst system.

The exact nature of the anion of this salt is not of fundamental importance; examples of salts that can be used within the scope of this invention include hydroxide, chloride, bromide, iodide,
Examples include carbonates, nitrates, and carboxylates having up to 12 carbon atoms.

Among these salts, the iodides, carbonates and carboxylates of lithium are particularly suitable for carrying out the invention. It is preferable to use lithium carboxylate having 5 or less carbon atoms,
Lithium acetate is particularly effective.

Generally, the amount of one (or more) lithium, magnesium or calcium salt used is such that the atomic ratio of metal (M) to nickel is between 1 and 100;
It can be less or more. Good results are obtained when the atomic ratio M/N i is between 2 and 25.

The catalyst system defined above is particularly effective for producing acetic anhydride by carbonylation of methyl acetate in the liquid phase.

As mentioned earlier, the reaction takes place in the liquid phase at pressures above atmospheric pressure. Generally, the reaction is carried out under a total pressure of 157-11 or higher, but no advantage is obtained using higher pressures such as 700 bar. A total pressure of 25 to 200 bar is preferred for the best practice of the invention.

Although the reaction temperature is approximately 140°C or higher, it is not necessary to use a high temperature such as 300°C.

Good results are obtained at temperatures within the range of 160° to 220°C.

Preferably, carbon monoxide is used in essentially pure form, for example as commercially available. However, impurities such as carbon dioxide, oxygen, methane and nitrogen may be present. Hydrogen is not harmful even in relatively high proportions.

At the end of the operation, the acetic anhydride produced is separated from the other components of the reaction medium by any suitable means, such as distillation.

The present invention will be described in detail below with reference to Examples, but these Examples do not limit the scope and spirit of the present invention.

BY in the examples (l represents the number of moles of acetic anhydride produced per 100 moles of introduced methyl acetate. Example 1: In a Hastelloy B2 autoclave with a volume of 1125 m1, 25 m11 of methyl acetate, 20 m1 of acetic anhydride, 8 mmol of nickel tetracarbonyl, 8 mmol of nickel tetracarbonyl, and 80 mmol of methyl chloride, 100 mmol of sodium iodide and 15-crown-
520 mmol is introduced. After closing the autoclave, it is brought to a pressure of 40 bar with carbon oxide. Start shaking using a reciprocating motion, and heat the autoclave with an annular heating furnace to 180° C. in about 20 minutes. The pressure inside the autoclave at that time was 64 bar. This pressure is then maintained and successive additions of carbon monoxide are introduced to 70 bar.

After reacting at 180° C. for 6 hours, shaking and heating are stopped. Cool and degas the autoclave. The reaction mixture is then analyzed. 79. ! 9/h×l of acetic anhydride is obtained: RY(l)-68°5 Control Example (a): Repeat Example 1 above without introducing crown ether. 1
After 2 hours at 80°C no reaction is observed.

Example 2: Methyl acetate (25 mA) and acetic anhydride (20 ml) were placed in a Hastelloy B2 autoclave with a capacity of 125 ml.

Nickel tetracarbonyl 8 mmol, methyl iodide 79
100 mmol of potassium iodide and 620 mmol of 18-crowns are introduced.

After closing the autoclave, a pressure of 40 bar is established with carbon oxide. Start shaking the reciprocating method and heat the autoclave using the annular heating furnace for about 20 minutes.
Heat to 80°C. The pressure inside the autoclave at that time was 64 bar.

The pressure is then kept constant and brought to a pressure of 70 bar by successively adding additional amounts of carbon monoxide.

After reacting at 180°C for 2 hours, stop shaking and heating. Cool and degas the autoclave. The reaction mixture is then analyzed. Obtain 40 g/hour x 16 acetic anhydride: RY (corresponding) -15° Example 6; In a Hastelloy B2 autoclave with a capacity of 125 mA, 25 ml of methyl acetate, 23 ml of acetic anhydride, 8 mmol of nickel tetracarbonyl, and 80 mmol of methyl iodide. , 100 mmol of sodium iodide, 15-crown-
520 mmol and 40 mmol of lithium acetate are introduced. After closing the autoclave -40 by carbon oxide
Establish bar pressure. Reciprocating power shaking is started, and the autoclave is heated to 180° C. in about 20 minutes using an annular heating furnace. The pressure inside the autoclave at that time was 64 bar. The pressure is then kept constant and additional amounts of carbon monoxide are introduced successively to bring the pressure to 70 bar.

Claims (9)

[Claims] (1) A method for producing acetic anhydride, which comprises carbonylating liquid phase methyl acetate in an anhydrous medium in the presence of effective amounts of nickel, methyl iodide, alkali metal iodide, and crown ether. (2) Total pressure is 15-700 bar, preferably 25-2
00 bar (1
). (3) Claims characterized in that the temperature is 140° to 600°C, preferably 160° to 220°G (
11 or the method described in (2). (4) The concentration of nickel is 5 to 5 for reaction medium 11.
A method according to any one of claims 1 to 3, characterized in that the amount is 2,000 milligram atoms. (5) When the concentration of nickel is 20 for reaction medium 11
4. A method according to claim 4, characterized in that the amount is ~1.000 milligram atoms. (6) The crown ether has formulas (I) to (■): [where m and n are 6 oxygen atoms contained in the macrocyclic ring]
-20 integers, a represents a phenylene, cyclohexylene or 2,3-naphthylene group, R represents an alkyl group having 4 or less carbon atoms or hydrogen, and U and V are the same or different groups. is the formula: %Formula%() (where p is an integer that may be O such that the number of oxygen atoms contained in the ring is 20 or less, and q
is an integer from 1 to 10, but when p is not 0, q is 2
The method according to any one of claims (1) to (5), characterized in that the polyether is chosen from macrocyclic polyethers represented by ]. . (7) Claims characterized in that the crown ether contains 5 to 10 oxygen atoms in the ring (6)
). (8) The crown ether has the formula (■): C in which a represents a phenylene, cyclohexylene or ha 2,6-naphthylene group, R represents hydrogen, and U and which may be the same or different groups; (1) represents a group having the formula: %formula%) (provided that p is equal to 1.2 or 6) ) to (the method described in any one of the above). (9) The method according to claim (1), characterized in that the crown ether is selected from 15-crown-5 and 18-crown-6. (1 to 10 methyl iodides per gram atom of nickel)
Claims (1) to (9) characterized in that it is present in the reaction medium in an amount of 0 mol, preferably 5 to 50 mol.
The method according to any one of the above. The method according to any one of claims (1) to α0), characterized in that all alkali metal iodides are selected from IJium and potassium iodide. (12+ Claims using alkali metal iodides in amounts of 0.2 to 50 moles per gram atom of nickel (
1) to (111). 03) Using the alkali metal iodide in an amount of 0.5 to 20 mol, preferably 1 to 10 mol per gram atom of nickel. A process according to any one of claims 1 to 1, characterized in that the ul crown ether is in a proportion of at least 5 moles of alkali metal iodide. (aD) The process according to any one of claims (1) to αa, characterized in that the proportion of the 151 crown ether is at most 1 mol per mol of the alkali metal iodide. Iodide 10
The method according to any one of claims (1) to a9, characterized in that the ratio is between 50 and 50 (mol). αη The method according to any one of claims (1) to Q61, characterized in that the reaction is further carried out in the presence of a lithium salt. Q81 The method according to claim Q7), wherein the lithium salt is a carboxylate having 12 or less carbon atoms. α■ The method according to claim αη or αtsuchi, characterized in that the lithium salt is lithium acetate.